David Ponce (Former Employee)

No abstract available.

A high-resolution aeromagnetic survey has defined a number of small dipolar anomalies indicating the presence of magnetic bodies buried beneath the surface of Crater Flat and the Amargosa Desert. Results of potential-field modeling indicate that isolated, small-volume, highly magnetic bodies embedded within the alluvial deposits of both areas produce the anomalies. Their physical...

During middle Miocene time, western North America was subject to flood-basalt volcanism, dike-swarm injection, and broad-scale fracturing and folding of the crust. We propose a simple model to account for these events and for a regional pattern of geologic and geophysical features. Aeromagnetic maps reveal some of the most important elements of this pattern, which are several narrow...

Geophysical maps of northern Nevada reveal at least three and possibly six large-scale arcuate features, one of which corresponds to the northern Nevada rift that possibly extends more than 1,000 km from the Oregon- Idaho border to southern Nevada. These features may reflect deep discontinuities within the earth's crust, possibly related to the impact of the Yellowstone hot spot. Because...

Description of the hydrogeologic framework of Antelope Valley and Bedell Flat in west-central Nevada adds to the general knowledge of regional ground-water flow north of the Reno-Sparks metropolitan area. The hydrogeologic framework is defined by the rocks and deposits that transmit ground water or impede its movement and by the combined thickness of Cenozoic deposits. When data are...

This report provides brief petrographic descriptions of rock samples collected from the vicinity of the Hayward Fault, Northern California. Two groups of rock samples are represented here: A set of six samples that were used for laboratory measurements of P- and S-wave velocity , strength, density, and porosity. This group was examined using standard petrographic microscope, scanning...